Comment 14 for bug 284874

I have the same problem -- cannot connect to the network with radvd and IPv6 configuration in network-manager set to automatic. It's not just IPv6, network-manager fails to connect at all overy any protocol when IPv6 configuration is set to automatic. For a while restarting network-manager (service network-manager restart) helped and it configured properly right after the restart but now it doesn't work at all, whether it's cable

avahi-daemon[1023]: Registering new address record for fe80::212:3fff:fef8:a592 on eth0.*.
NetworkManager: <info> Device 'eth0' IP6 addrconf timed out or failed.
NetworkManager: <info> Activation (eth0) Stage 4 of 5 (IP6 Configure Timeout) scheduled...
NetworkManager: <info> Activation (eth0) Stage 4 of 5 (IP6 Configure Timeout) started...
NetworkManager: <info> (eth0): device state change: 7 -> 9 (reason 5)
NetworkManager: <info> Marking connection 'Auto eth0' invalid.
NetworkManager: <info> Activation (eth0) failed.
NetworkManager: <info> Activation (eth0) Stage 4 of 5 (IP6 Configure Timeout) complete.
NetworkManager: <info> (eth0): device state change: 9 -> 3 (reason 0)
NetworkManager: <info> (eth0): deactivating device (reason: 0).
NetworkManager: <info> (eth0): canceled DHCP transaction, dhcp client pid 2096

or wifi

NetworkManager: <info> Device 'eth1' IP6 addrconf timed out or failed.
NetworkManager: <info> Activation (eth1) Stage 4 of 5 (IP6 Configure Timeout) scheduled...
NetworkManager: <info> Activation (eth1) Stage 4 of 5 (IP6 Configure Timeout) started...
NetworkManager: <info> (eth1): device state change: 7 -> 9 (reason 5)
NetworkManager: <info> Activation (eth1) failed for access point (soynet)
NetworkManager: <info> Marking connection 'Auto soynet' invalid.
NetworkManager: <info> Activation (eth1) failed.
NetworkManager: <info> Activation (eth1) Stage 4 of 5 (IP6 Configure Timeout) complete.
NetworkManager: <info> (eth1): device state change: 9 -> 3 (reason 0)
NetworkManager: <info> (eth1): deactivating device (reason: 0).
NetworkManager: <info> (eth1): canceled DHCP transaction, dhcp client pid 2105
wpa_supplicant[1201]: CTRL-EVENT-DISCONNECTED - Disconnect event - remove keys

network-manager just times out and disconnects. The prefix is properly advertised on the network:

#
# radvd configuration generated by radvdump 1.6
# based on Router Advertisement from fe80::ecd9:12ff:fe66:3cce
# received by interface br-lan
#

interface br-lan
{
 AdvSendAdvert on;
 # Note: {Min,Max}RtrAdvInterval cannot be obtained with radvdump
 AdvManagedFlag off;
 AdvOtherConfigFlag off;
 AdvReachableTime 0;
 AdvRetransTimer 0;
 AdvCurHopLimit 64;
 AdvDefaultLifetime 1800;
 AdvHomeAgentFlag off;
 AdvDefaultPreference medium;
 AdvSourceLLAddress on;

 prefix my:correct:prefix::/64
 {
  AdvValidLifetime 86400;
  AdvPreferredLifetime 14400;
  AdvOnLink on;
  AdvAutonomous on;
  AdvRouterAddr on;
 }; # End of prefix definition

 RDNSS fe80::ecd9:12ff:fe66:3cce
 {
  AdvRDNSSPreference 8;
  AdvRDNSSOpen off;
  AdvRDNSSLifetime 600;
 }; # End of RDNSS definition

Another machine running Ubuntu Studio without network-manager can autoconfigure just fine.